Irish fighter, McGregor, who was wearing a suit with “F**K YOU” in tiny letters artfully embroidered into it dozens of times, appeared before his fight with Floyd Mayweather on stage to engage in some trash talk.

As for Mayweather, he was relaxed about the name calling, telling TMZ Sports, "Racist? I don't know what that got to do with race. This is a boxing match. I don't know what that got to do with no racists."

The use of the word ‘boy’ is highly sensitive in the United States and is widely considered a racist and offensive term when used by white men addressing black males of whatever age.

A former employee of Tyson Foods, John Hithon, sued because the use of the term in the workplace demonstrated racial bias and that the word was, "If not a proxy for 'nigger,' [boy] is at the very least a close cousin."

The case meandered through the court system for the best part of two decades.

And it’s not even McGregor’s first foray into racially charged language: he had previously derided Mayweather as a “malteaser with eyeballs” and last year at another pre-fight press conference he described Mexican American, Nate Diaz, as a “cholo gangster from the hood”.